Electric discharge device construction



Sept. 26, 1950 R. J. BONDLEY 2,523,750

ELECTRIC DISCHARGE DEVICE CONSTRUCTION Filed Oct. 1, 1947 A? I /o f y /Z I I I 7 I 4 m, I a

a j/ I hmverwtor: Ralph J. Bonclley,

Patented Sept. 26, 1956 ELECTRIC DISCHARGE DEVICE CONSTRUCTION Ralph J. Bondley, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application October 1, 1947, SerialNo. 7731,349

10 Claims. 1

The present invention relates to electric dis- Charge devices and more particularly to an improved electrode construction :and arrangement which improves the operation of the electron discharge device.

Beginning at the lower end, of the high frequency band i. e. at frequencies of the order of 190 megacycles it becomes difiicult and often physicall impossible to use conventional coil and capacitor type circuits with tubes usually employed at lower frequencies. The top frequency at which the conventional coil and capacitor type circuit is capable of operating with practical effectiveness is set by the internal capacity of the tube and by the length and inductance of the lead-in wires of the tube. The

disc type triodeseffectively extend the frequency range of tubes employed at the lower frequencies especially'whenused in grounded grid or grid separation circuits. of triodes is limited to a considerable degree by the capacit existing between the cathode and anode: At high frequencies; thiscapacity-even though very small is suflicient to cause the circuits to oscillate and to perform in other undesired ways.

A- screen grid tube: eliminates" the oscillation trouble. The chief. difficulty with the screen grid tube is the mechanical. complexity encountered in the screen gridby-pass condenser. If the screen; section is brought out through the tube envelope by a disc. seal the high frequency return can be effected by: attaching another; circuit element such as asection of, transmission lineto this disc and thentuning this new circuit 1 shift is minimized. By the: present. invention the length of the transmission-line fo'rmed by the condenser plates is made small: so tl'ratthephase .:.shift is notappreciable; The radialdimension of the condenser corresponding to the length- However, the gain lithe-length of'the transmission line formed by thecondenser plates is smallthe phase wise dimension of the transmission line mentioned above can be made small for a given value of capacity by the peripheral distribution of the bypass capacity rather than a radial distribution of the by-pass capacity.

The present invention overcomes the difficulties that arise with the conventional disc type tetrode construction by incorporating the screen igrid by-pass condenser inside the tube itself in such a manner that the circuit in which the tetrode is used is no more complicated that the conventional triode circuit. However, the advantages in using a tetrode are still obtained. Further advantages of the improved construction are several. The by-pass isadded to the circuit right at the grids where it is most effective rather than externally. The screen grid supply voltage connection is made to a point corresponding to high frequency ground so that none of the high frequency escapes through the screen supply voltage lead and no other bypass condensers are necessary. The arrangement does not require tuning and, therefore, is not frequency sensitive. When vacuum is used as a dielectric medium, dielectric losses are negligible. With the capacity construction of the invention the input currents flow along one surface of the non-active portion of the grid member and the output currents flow along a different surface of the non-active portion of the grid member, thus, feedback effects are minimized.

It is an object of the present invention to provide a new and improved electric discharge de- Vice.

It is another object of the present invention to provide a new and improved capacity construction incorporated within the electrical discharge device.

Further objects and advantages of my invention will be apparent as the following description proceeds and its scope will be pointed out in the appended claims.

The single figure of the drawing is an elevation view in section of one illustrative assembly of an electric discharge device embodying the invention. Referring to the drawing, the electric discharge device may be assembled from two halves. The right half of the tube comprises an annular shaped base member other suitable material, a cylindrical anode assembly 2, and an annular shaped glass enclosure member 3; The anode assembly 2 comprises: a cylindrical iron support member 6 and a disc shaped face member I of copper or other suit- I, of copper or .active namely, member M, is completely surrounded by able material The glass member 3 is connected mechanically to the anode assembly member 2 by means of the annular member "3', which may be made from any of the suitable glass to metal sealing materials well known in the art, such as alloys of iron, nickel and cobalt. The glass member 3 is connected to the base member I by means of the annular member 5 which is made of the same material as member 4.

The left half of the electric discharge device comprises a left annular base member 8 of copper or other suitable material, the glass enclosure member 9 of generally annular shape, and a cathode member ill of generally cylindrical shape including cathode Illa. The glass member 9 is mechanically connected to the base member 8 by means of the annular member I! which is made of the same material as member l. The glass member 5 is mechanically connected to the cathode assembly by means of metallic annular member l2 which is made of the same material as member 4. To the left base member 8 is connected grid member l3 of annular disc shape and made in a manner well known in the art. Screen grid supporting member M, of suitable metal construction and annular disc shaped, is supported by grommet-like insulators l5 and IE on base member 8. Annular screen grid member I! is suitab y attached to screen supporting member I l. Insulator members l8 and i9 preferably discvlike and preferably held by pins, not shown, in

member [4 assist in rigidly supporting member I6 between members i and 8. In the final assembly members I and 3 are hermetically sealed together by atomic hydrogen welding or other suitable means. The techniques involved in fabricating a tube of this kind are well known to one skilled in the art.

It will be apparent from the foregoing that in operation the grid members l3 and i? will be dielectric. It will be noted also that the structure having a common unidirectional potential with grid member !3, namely, members I 8, substantially com letely surrounds member i l which means that it is completely shielded by the grid structure which may be operated at ground potential. Thus in effect, what may be termed an inportion of the screen. grid structure,

what be termed as an inactive portion of the structure common to grid member l3 in unidirectional potential. The active portions by which is meant those portions directly affecting the electron discharge of the tube, are freel exposed to the discharge, From this it will be apparent that any structure having opposed walls such as members i and 8 substantially completely enclosing a screen grid support and having aligned apertures across which the active grid portions are positioned will serve the purpose of the invention.

While the present invention has been described in connection with a particular embodiment of my invention it will be obvious to those skilled in the art, changes and modifications may be made without departing from my invention in its broader aspects and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

(ill

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric discharge device comprising an envelope, a first grid member, a second grid member, said second grid member having a radially extending non-active portion said first grid member including structure surroundin substantially all the effective surface of the nonactive portion of said second grid member to form with said second grid member a capacitor.

2. An electric discharge device including an anode, a cathode and a grid structure intermediate therebetween comprising metallic members defining a substantially closed hollow chamber having juxtaposed opposing walls having aligned apertures through which an electrical discharge between said anode and cathode may pass, a conductive member within. said chamber having a conductive portion supported between and in insulated relationship to said walls and having a third aperture aligned with said first mentioned apertures, a grid supported across one of said first mentioned apertures, and a grid supported across said third aperture.

3. A device as in claim 2 wherein said structure comprises a cylinder said walls comprising annular end faces of said cylinder, said conductive member comprising an annular member aligned with said end faces.

4. A grid structure comprising metallic'members defining a substantially closed hollow chamber having juxtaposed opposing walls having aligned apertures through which an electrical discharge is adapted to pass, a conductive member within said chamber having a conductive portion supported between and in insulated relationship to said walls and having a third aperture aligned with said first mentioned apertures, a grid supported across one of said first mentioned apertures, and a grid supported across said third aperture.

5. A structure as in claim 4 wherein said structure comprises a cylinder said walls comprising annular end faces of said cylinder, said conductive member comprising an annular mem ber aligned with. said end faces.

6. An electric discharge device including an anode, a cathode and a grid structure intermediate therebetween comprising metallic members defining a substantially closed hollow chamber having juxtaposed opposing walls having aligned apertures through which an electrical discharge between said anode and cathode may pass, a conductive member within said chamber having a conductive portion supported between and in insulated relationship to said walls having a third aperture aligned with said first mentioned apertures, said conductive member with the inside surface of said grid structure forming a capacitor, and a grid supported across said third aperture.

7. A grid structure comprising metallic members defining a substantially closed hollow chamber having juxtaposed opposing walls having aligned apertures through which an electrical discharge is adapted to pass, a conductive mem- -ber within said chamber having a conductive portion supported between and in insulated relationship to said walls and having a third aperture aligned with said first mentioned apertures, said conductive member with the inside surface of said grid structure forming a capacitor, a grid supported across one of said first mentioned apertures, and a grid supported across said third aperture.

8. An electric discharge device comprising a grid structure, said grid structure including a hollow cylinder with two bases, one of said bases having an active portion and an inactive portion, the second of said bases having an inactive portion, a disc shaped grid member including an active portion and an inactive portion, said grid member being located within and parallel to the bases of said cylinder, said inactive portion of said grid member being substantially surrounded by the inactive portion of said grid structure and forming therewith a capacitor, and means for making external electrical contact to said grid member through the inactive portion of said grid structure.

9. An electric discharge device comprising a grid member, said grid member being in the form of a hollow'cylinder, one base of said cylinder having an active portion and an inactive portion, the second base of said cylinder having an inactive portion, a second disc shaped grid member including an active portion and an inactive portion, said second grid member being located parallel to and within the bases of said cylinder, the inactive portion of said second grid member bein substantially surrounded by the inactive portion of said first grid member and forming therewith a capacitor which is completely contained within the enclosure of said discharge device and in which substantially all of the inactive surface of said second grid'member is effective as a capacitor.

10. An electric discharge device comprising a grid member, said grid member being in the form of a hollow cylinder, one base of said cylinder having an active portion and an inactive portion, the second base of said cylinder having an inactive portion, a, second disc shaped grid member including an active portion and an inactive portion, said second grid member being located parallel to and within the bases of said cylinder, the inactive portion of said second grid member being substantially surrounded by the inactive portion of said first grid member and forming therewith a capacitor which is completely contained within the enclosures of said discharge device and in which substantially all of the inactive surface of said second grid member is effective as a capacitor, an envelope member including a cathode, said envelope member being attached to the first base of said first grid member, a second envelope member including an anode, said second envelope member being attached to the second base of said first grid member.

RALPH J. BONDLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,062,319 Laico Dec. 1, 1936 2,220,839 Hahn Nov. 5, 194.0 2,227,372 Webster et al Dec. 31, 1940 2,256,293 Salzberg Sept. 16, 1941 

